The purposes of this study are to: (1) determine the nature and extent of prescription drug utilization in a representative sample of 1,026 adults in a defined population: (2) conduct a multivariate sociopsychological analysis of the factors which might predict and explain variations in prescription drug utilization; and (3) test three explanatory models used t account for sex differences in the utilization of prescription drugs. The study will determine whether the study participants used any prescription drugs during a 24-month period, what types of prescription drugs were used, how many different types were used concomitantly, and the duration and extent of use. The multivariate analysis will focus on a variety of independent variables, including: the nature and extent of morbidity; the number and location of physician visits; the participants' age, gender, and other sociodemographic characteristics; level of psychological distress; level of role strain; attitudes toward illness and medical care; type of insurance coverage and perceived access to care; and usage of alternative modes of drug therapy (i.e., nonprescription drugs). Four sources of data will be linked and analyzed: objective data obtained from the participants' pharmacy records, medical record data, face-to-face interview data, and self-administered questionnaire data. The data will be analyzed with various statistical techniques, including multiple regression techniques. Since there are few epidemiological studies that examine how and why people use various kinds of prescription drugs, the study should make a significant contribution to our understanding of this type of illness behavior and enable us to clarify the issues that need to be explored in future work.